Field of Invention
This invention relates to processes for producing hydrofluoroolefins. More particularly, this process relates to processes for producing hydrofluoroolefins via dehydrohalogenation.
Description of Related Art
Certain hydrofluoroolefins (HFOs), such as HFO-1225zc, HFO-1234yf and HFO-1234ze, have zero ozone depletion potential and have very low global-warming potential such that they are desirable replacement for hydrofluorocarbons (HFCs) such as HFC-134a and HFC-245fa in applications such as refrigeration, foam blowing, etc.
One method for synthesizing hydrofluoroolefins involves dehydrohalogenation of a halogenated alkane, such as hydrofluorocarbons and hydrochlorofluorocarbons (HCFCs). Such dehydrohalogenation reactions can occur as a liquid or gas phase reaction.
For liquid phase dehydrohalogenation reactions, one method involves reacting the HCFC or HFC in the presence of a KOH solution which simultaneously neutralizes the HF or HCl according to the reactions below:HCFC-235fa+KOH(aq)→HFO-1225zc+KF(aq)+WaterHFC-236fa+KOH(aq)→HFO-1225zc+KF(aq)+WaterHFC-236ea+KOH(aq)→HFO-1225ye(E)+HFO-1225ye(Z)+KF(aq)+WaterHFC-245eb+KOH(aq)→HFO-1234yf+KF(aq)+WaterHFC-245fa+KOH(aq)→HFO-1234ze(E)+HFO-1234ze(Z)+KF(aq)+Water
Conventionally, such liquid phase reactions are performed as a batch process wherein the reactants are charged into a batch reactor without regard to their order of addition. Typically, the charged reactants are allowed to react for a period of time followed by recovery of the product. This mode of operation results in long batch times as well as large amounts of moisture in the crude product. Hence there is a need to design a more economical and more effective means of carrying out the above reactions.